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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Among the most significant conclusions in the report is that we could meet as much as 43% of global energy demand with renewable sources by 2030, and up to 77% by 2050 (renewable energies accounted for 13% in 2008), although based on the bulk of the 164 scenarios examined, closer to 30% renewable penetration appears more realistic. Certain individuals have attempted to manufacture controversy about the 77% renewable penetration scenario (see the associated McManufactured Controversy' post), but in reality it's not even a terribly aggressive target from a technological standpoint. For example, we have previously discussed the Ecofys plan to meet 100% of global energy demand with renewables by 2050, and the Jacobsen and Delucchi plan to meet 100% of demand with just wind, water, and solar energy in 2050 (also see the Advanced rebuttal to "Renewables can't provide baseload power"). Compared to those plans, a 77% goal is relatively muted. It may be unrealistic from a political standpoint, but that question is beyond the scope of this report.

According to SRREN, renewables are already developing rapidly. Of the 300 gigawatts (GW) of new electricity-generating power plants added globally from 2008 to 2009, nearly half (140 GW) came from renewable sources. In the European Union, the share of renewable to total energy installment was even higher, at 62%.

The report also found that global availability and obtainability of renewable energy will not limit continued growth, because the global technical potential exceeds the primary energy use, which was 492 exajoules (EJ = 1018 Joules) in 2008 (Table 1).

SRREN found that sufficient investments in renewable energy to stabilize atmospheric CO2 levels at 440 ppm (approximately corresponding to the 'danger limit' of 2°C warming above pre-industrial levels) would cost approximately $5.1 trillion from 2011 to 2020 and $7.2 trillion from 2021 to 2030, globally. Although it sounds like a large amount of money, this represents less than 1% of the global gross domestic product (GDP).

The report also notes that as we have previously discussed, the external costs of coal combustion (primarily due to health impacts and climate change), which are not currently reflected in the market price of coal power, increase the true cost of coal several times over. The external costs of renewable energy sources are much lower (Figure 1). While the external costs for coal fired power plants are at least 7.2 cents per kilowatt-hour (kWh), they are less than 0.2 cents/kWh for wind turbines. If the external damages are considered costs of wind energy are likely cheaper than those of coal energy (Jacobson and Masters 2001).

Figure 1: Illustration of external costs due to the lifecycle of electricity production based on renewable energy and fossil energy. Note the logarithmic scale of the figure. The blue lines indicate the range of the external cost due to climate change and the red lines indicate the range of the external costs due to air pollutant health effects.

An argument that many "skeptics" like to make (including John Christy) is that historically, economic development has been strongly correlated with increasing energy use and growth of greenhouse gas (GHG) emissions. This is true, since the majority of energy production has historically come from fossil fuels. Thus, the "skeptics" argue, transitioning away from fossil fuels to renewable energy will cripple the economic growth of developing nations.

However, this is simply a logical fallacy. Economic growth correlates well with energy use, but there's no reason that energy has to come from fossil fuels. It's just that historically, the market price (though not the actual net cost) of fossil fuels has been very low. However, the SRREN notes that renewable energy can help decouple that correlation between economic growth and GHG emissions, contributing to sustainable development. Another key to meeting increasing energy mands from developing countries with renewable power is the rapidly decreasing cost of these technologies, particularly solar photovoltaic (Figure 2).

Figure 2: Decreasing average price of solar PV and wind as global installed capacity of these technologies has grown

Of course it's not all sunshine and rainbows. Meeting the $5.1 trillion global renewable energy investment from 2011 to 2020 will require a five-fold increase from current investment levels. And of course there is the political challenge involved in implementing the necessary policies to allow this renewable energy investment increase to happen. For example, putting a price on carbon emissions, which will more accurately reflect the true cost of fossil fuel combustion in their market price, and make renewable energy more financially competetive. However, even though doing so would be economically beneficial, as the SRREN notes, there is a great deal of political resistance to implementing a carbon price in many countries.

To sum up, in this report the IPCC finds that we can give ourselves a chance to keep global warming below the 'danger limit' with an investment of less than 1% of global GDP in renewable energy. This will also help us de-couple economic development from GHG emissions, and in fact will benefit the economy by avoiding the harm to public health and the climate associated with burning fossil fuels. However, accomplishing this major transition from fossil fuels to renewable energy will be very challenging, particularly from a political standpoint in terms of implementing the necessary policies.

Lynas has not raised any substantive criticisms of the report. He's unhappy that the 77% plan phases out nuclear power, but that's neither here nor there - the plan is both technically and economically feasible.

As Rob suggests, to discuss the manufactured controversy and ad hominem attacks, please see the sister post linked at the end of this article.

A question that always arises in my mind is: What is the difference in the investment cost of renewables and the investment cost in replacing existing fossil energy plants, plus the infrastructure that supports them, as their economic lifetime expires? I hardly ever see this addressed except that renewable plant costs are, in general, going down and fossil plant costs are going up.

I also note that the geothermal sources are conservative low hanging fruit estimates compared to the MIT study that gives estimates of 14,000ZJ, 200ZJ - 2000ZJ potentially extractable, for just the continental US.

luminous - that's a bit of a tricky question, because it depends what you're factoring into the price of a new coal plant. In this post I mentioned the true cost of coal power - in short, the market price is cheap because it doesn't reflect the costs of the climate change and impacts on public health (which economists call "externalities").

If you don't include those external costs, coal is cheaper than most renewable energy sources (onshore wind is close). If you do include those external costs, most renewable sources are already cheaper than new coal plants. Putting a price on carbon emissions would be a major step in making the market price of coal more accurately reflect its true cost.

Basically in the real world, it's cheaper to replace old power plants with renewables. But in the current market, it's usually cheaper for an electric utility to replace them with new coal plants (or natural gas). Which is why so many of us (including most economists) are pushing for a price on carbon emissions.

Yes Rob, sometime in the next decade solar PV is expected to meet that threshold. As Figure 2 in the post shows, the costs are really dropping rapidly as production continues to ramp up. But remember that's the market price of coal. If there were a price on carbon emissions, solar PV would probably already be cheaper.

Almost all my optimism is on this one fact. Once the cost of PVs drops below coal then the economic incentive becomes to produce cheaper energy that just happens to also be cleaner. Those investment levels become FAR easier to hit when there is a clear economic advantage.

The old Chinese saying is, "May you live in interesting times." Well, we are certainly living those times today. My sense is that this next decade will be pivotal for humanity on a lot of levels.

We trained hard…but it seemed that every time we were beginning to form up into teams we would be reorganized. I was soon to learn later in life that we tend to meet any new situation by reorganizing; and what a wonderful method it can be for creating the illusion of progress while producing confusion, inefficiency and demoralization.

The ancient Roman's actually invented urban legends, but I think that belief itself is only an urban legend.

It is interesting to note that the ancient Greeks, on the other hand, invented recursion when their historians decided that the only peoples worth researching were themselves.

How does this relate to the post and climate change? It doesn't, but if you delete this comment, you will be doomed to seven years of bad luck, which interestingly enough is a superstition which traces back to feudal Japan...

3, dana1981 - 'Lynas has not raised any substantive criticisms of the report. He's unhappy that the 77% plan phases out nuclear power, but that's neither here nor there - the plan is both technically and economically feasible.'

I agree that Lynas' arguments are low on substance but I can't really see how Teske's scenario is really plausible, at least with the all the details in the report:

The way they achieve 77% renewables without nuclear and CCS is to reduce the total energy demand. This is despite world population increasing to 9 billion. With all this happening they still suggest that GDP per capita can increase at the same speed as zero-mitigation scenarios.

I'm certainly not an expert in economics but I can't see how this is feasible.

pauls - the Ecofys report (linked in the post above) also has energy demand lower in 2050. I think Jacobsen and Delucchi do too. It's really not that uncommon. For one thing, just switching to renewable energy increases efficiency, because fossil fuels and nuclear waste a lot of energy by continuing to run at their peak during off-peak hours. As I recall, Jacobsen and Delucchi found that switching to renewables would decrease energy needs by 30% by itself. Then you add more efficient buildings and vehicles, etc., and the Teske efficiency scenario is definitely plausible.

'Climate impacts were monetized using estimates
of the social cost of carbon—the valuation of the
damages due to emissions of one metric ton of carbon,
of $30/ton of CO2equivalent (CO2e),20 with
low and high estimates of $10/ton and $100/ton.
There is uncertainty around the total cost of climate
change and its present value, thus uncertainty concerning
the social cost of carbon derived from the
total costs.'

I couldn't see any great justification of either the $10 or the $100 extremities?

It's an interesting subject - clearly there are externalities of coal, as there are externalities of many activities, the climate change externality must be the hardest to get a grip of - what is the external climate cost of a US coal plant etc.

I see they use $7.5m for a value of a life - it's not clear, or is it, that many US lives (which determine the $7.5m value) will be lost from CO2?

According to SRREN, renewables are already developing rapidly. Of the 300 gigawatts (GW) of new electricity-generating power plants added globally from 2008 to 2009, nearly half (140 GW) came from renewable sources.

Yes, I read that too in the summary for policy makers and it is a poor and misleading representation of the true state of affairs because it does not mention capacity factor.

The correct way to gauge the contributions of new renewables build is to weight the nameplate capacity by the capacity factor to determine how much of electricity that will be generated from the new build will be low emission. The picture will be far less rosy with PV nominally up to about 20% (12% in Germany) on-shore wind nominally up to 30% (reportedly 17% in Germany), hydro very much site specific but around 45% worldwide. Etc.

I don't know the exact figures, but it is very unlikely that renewables would represent more than 25% of new build and quite possibly considerably less when correctly assessed.

Dana1981@3 Lynas has not raised any substantive criticisms of the report. He's unhappy that the 77% plan phases out nuclear power, but that's neither here nor there - the plan is both technically and economically feasible.

Of course phasing out nuclear power is pertinent - it's a low-carbon power source. If the scenario in the Greenpeace report doesn't pan out then all we've done is increase carbon emissions for little gain.

pauls @12, from my reading of the report, the scenario assumes a reduction not in demand, but in energy intensity, ie, Kilowatts used per unit GDP produced. Further, they assume a reduction in energy intensity at the same rate as is currently being achieved in the EU, and to a target level which has already been achieved in Japan. Prima facie, that is not an implausible target.

If you want to pursue this energy intensity argument in the EU and Japan, then the purported improvements in energy intensity must take into the account the rising embedded energy in imported goods. Do they?

While there is trend in the developed world towards a greater proportion of economic activity to be in service industries eg leisure, education, health etc, that are in general less resource intensive (including energy), extrapolating this to the developing world on a scale that would reduce energy demand seems a bridge too far.

With another two billion people on the planet expected by 2050 and over one and a half billion currently without electricity the potential for enormous increase in energy demand is quite plain. This does not mean that all these people will be lifted by magic out of poverty to a reasonable standard of living, but the historical trend is quite obvious and in the absence of some catastrophic event quite irreversible.

It is frequently (and quite reasonably) argued that addressing climate change is about managing risk. Using dubious assumptions about worldwide energy demand being reduced by 2050 seems to me to represent extreme risk. It is far from impossible that demand could simply explode.

This report suggests that world energy consumption increased by 5% in 2010. Even allowing for the effects of the GFC - Ouch!

quokka: you're forgetting that the actual efficiency of use of primary energy is, in many cases, very very low, e.g. coal fired power stations rarely convert more than a third of the primary (thermal) energy into useable electricity. Burning liquid fuels in car & truck engines is even less thermally efficient - <20% for petrol(gasoline) engines, maybe as high as 40% for a well-tuned diesel. Replacing a petrol-powered car with an electric one will result in more efficient energy use, especially if you charge it with electricity that doesn't come from burning fossil fuels.

And that's completely ignoring the issue of energy wastage, which is a far bigger problem (e.g. driving a 12mpg truck to your desk job, when you could be catching public transport). Many (most?) industrial users can significantly reduce energy usage with no changes to their output at all. Those that make the effort usually reap the benefits, saving tens or even hundreds of thousands of dollars on their energy bills (or millions, for large industries). You can hardly claim that most industries in China that produce goods for Europe & Japan have been optimised in terms of their energy use.

That's not to say that rolling out energy efficiency across the entire global economy would be easy, nor cheap. But it would pay for itself quite quickly.

Whether it would be enough to entirely offset growth in world economic activity, I don't know.

Partially true, but in some of the high renewables scenarios, there is a lot of biomass. The issue of the efficiency of heat engines is not going to go away any time soon.

We don't even know yet how widespread the deployment of EVs is likely to be. It may turn out that carbon neutral synfuels of some type have a big role to play. Again the issue of heat engine efficiency looms large.

I completely agree that there is an urgent need to dramatically improve public transport, but sometimes it is far more difficult than is commonly supposed. I spent a decade or so working in London as a contractor - some short term and some long term contracts so I got around a bit. I always had a car but I would rather slam my finger in a car door than drive to work every day as opposed to use train or underground. A lot of people in London share that sentiment.

London has an extensive and heavily used rail and underground system and quite good local bus services. But the rail and tube is essentially a spoke network. If you need to travel any substantial distance across those spokes, then the buses take way too long and there is no alternative but to drive. This is why the M25 ring motorway (six lanes in each direction in parts) is the busiest motorway in Europe. There is no easy, and certainly no cheap solution to this problem. The existing rail and tube system has taken over a century to build.

London is certainly not the whole world, but each public transport network will have it's own set of issues to address, and some of those issues are damned difficult to resolve and are going to take many decades, if indeed they are ever addressed.

What I see repeatedly is an attempt to shoehorn purported solutions into the best of all possible worlds. It is done, not because those worlds are the ones that we are most likely to inhabit, but because of emotional attachment to alleged solutions.

quokka - I'm actually of the opinion that synthetic fuels (carbon neutral) will be part of the ongoing solution. There are several in development now, including (as I've referred to before) one for aviation gas that is in the US FAA (Federal Aviation Administration) approval cycle (Swift Fuels).

quakka:
"If you want to pursue this energy intensity argument in the EU and Japan, then the purported improvements in energy intensity must take into the account the rising embedded energy in imported goods. Do they?"

The reason is that emissions need to be accounted for based on consumption and government responsibility.
If production is exported but the nation that exported the production continues to consume at the same rate, then effectively the consumer nation is held responsible for the emissions of the producer country.

The consumer nation does have a choice as to how much it consumes and hence is responsible.

An interesting comparison and 'other factor' here is comparisons to military spending. Dana's figures give a cost of $500-$700 Billion per year. World military spending is around 1.3 to 1.5 Trillion per year. How much of that military spending is really about protecting energy security?

And consider how much military spending is actually 'wasted'. Not spent for its intended purpose. Australia is replacing its Leopard tanks with wizz-bang Abrahms, replacing its F111 & FA18 fleet, its entire destroyer & frigate fleet, planning for the replacement of its submarine fleet etc. And they have hardly ever fired a shot in anger. A small number of sorties in the Iraq war, a few small bombardments around Basra. The pasrts of our military that have carried the heavy lifting for many years are the special forces units, military transport aircraft and transport ships. Most oif the rest has been ever ready but not used.

A world with fewer Big Power confrontations and Energy Security missions, oops I mean Carrier Battle Group deployments, is surely a world where we can still have our military security at a fraction of the cost. Isn't that a hidden cost advantage of moving away from energy sources that need to be transported around the world?

14, dana1981 - I certainly don't dispute that energy demand can be reduced over time with improved efficiencies. What I can't see is how this can be coincident with unfettered growth in per capita GDP. Essentially Teske 2010 claims that economic growth can be decoupled from energy usage altogether (normally 'decoupling' refers simply to breaking the link bewteen economic growth and fossil fuel use). Is there anything which can back this up?

20, Tom Curtis - Table 10.3 in the report shows figures for both Energy Demand and Energy Intensity. While all four of the featured scenarios show reductions in Energy Intensity by 2050, ER-2010 (Teske) is a huge outlier in producing a reduction in Energy Demand by 2050.

Pauls @29, from Teske et al 2010, the difference between their Energy Revolution scenario and their "advanced Energy Revolution" scenario consists in the assumption that energy use in transport will be reduced by the wide spread adoption of public transport and/or electrical vehicles; and the assumption that heating will be done using solar, geothermal or waste heat sources, thus not requiring independent energy generation to drive it. Total energy demand for normal power purposes increases by the same amount as in their less ambitious Energy Revolution scenario, and in fact a little bit above that to power the electrical vehicles.

However, for base industrial and domestic power supply, the scenario assumes reduced energy intensity but increased overall demand due to a population growth of 2.48 billion and a per capita GDP growth rate of approximately 2% per annum.

The UK Climate Change Committee doesn't even mention solar or geothermal as significant players in renewable heating in the Renewable Energy Review. They see heat pumps and on a more limited scale resistive heating as the primary technologies for renewable heat. They set aside district heating using waste heat from nuclear or CCS power generators as a potential source but requiring further study.

On heat pumps they estimate:

Although there are limits on the suitability of these technologies, our analysis suggests that these could meet 55% to 75% of residential heat demand and around 70% to 90% of non-residential space heat demand in the UK.

Assumptions that heating will not require independent energy generation to drive it seem extremely dubious to me (and also it would seem to the CCC).

Wind power plant investment costs rose from 2004 to 2009 (Figure 7.20), an increase primarily caused by the rising price of wind turbines (Wiser and Bolinger, 2010). Those price increases have been attributed to a number of factors. Increased rotor diameters and hub heights have enhanced the energy capture of modern wind turbines, for example, but those performance improvements have come with increased turbine costs, measured on a dollar per kW basis. The costs of raw materials, including steel, copper, cement, aluminium and carbon fibre, also rose sharply from 2004 through mid-2008 as a result of strong global economic growth. The strong demand for wind turbines over this period also put upward pressure on labour costs, and enabled turbine manufacturers and their component suppliers to boost profit margins. Strong demand, in excess of available supply, also placed particular pressure on critical components such as gearboxes and bearings (Blanco, 2009).7.8.3

quokka @33, I just reported on the claims of Teske et al 2010. However, your source estimates that waste industrial heat could supply "around 70% to 90% of non-residential space heat" in the UK. That is a very large amount of heating which requires only pumping (much less energy expensive), and if implemented would represent a large reduction in primary demand for electricity.

It appears that your assumptions are exactly that, and are not supported by your chosen source.

In this case, then, I will have to disagree with the CCC and you. It is certainly possible to design or refurbish buildings in Germany or Scandinavia to require little or not direct heating. If it works in Scandinavia, it will also work in Britain, so it is certainly feasible to reduce primary energy requirements by shifting to renewable heating.

I think it needs to be emphasized again that Teske's is just one scenario. It's technologically and economically viable, but it may not be politically viable to, for example, dramatically increase use of public transportation and decrease individual passenger vehicle use. As I said, this report doesn't evaluate what's politically viable. However, it certainly looks to me like we could meet the Teske plan if we had the political will to do so.

Dana; 'political will' really means making political choices on what to spend public money on and what policies to push. Germany made a commitment to reduce emissions 80% and generate 80% of their energy from renewables by 2050. They've made that choice for economic reasons - to ramp up their low-carbon, super hi- efficiency technologies that they can sell to the rest of us. I call that a smart choice.

I agree Stephen. A lot of EU countries are making those smart choices. China is actually doing pretty well too. But fossil fuels are very entrenched in many others (i.e. USA, Canada, Australia), preventing us from having the political will to make the smart choices.

I call Germany's decision to phase out nuclear power dumb not smart. There is absolutely no way that it will not result in emissions higher than they would have been if nuclear was retained and operated in parallel with new renewables build. It cannot be otherwise.

The UK now has a "legally binding" commitment to 50% emissions reductions by 2027, so it would be well to study it's plans too. Of course for all nations, one does not have have to question the sincerity of commitments, to observe that what is being said may well not be what is achieved. It's all still words at the moment and does not constitute "proof" in any sense that any particular path is anything like optimal.

There is an unfortunate habit of lumping all renewables together and make implications about future growth of renewables based on their share of current electricity generation. This obscures rather than informs. It it overwhelmingly solar/wind that must be grown to do the heavy lifting, if renewables alone are to deliver the goods.

Today, the situation is that in OECD countries nuclear supplies 22% of electricity, solar/wind/geothermal 4%. In Germany solar/wind/geo supplies 7.7%. (Source IEA Monthly Electricity Stats). If all the OECD shut down nuclear over the next decade, it would require the current solar/wind group to be expanded by a factor of six or more just to maintain the current level of emissions in electricity generation. What hope for emissions reductions then? This is how important nuclear is.

I believe that the UK now has the highest commitment to emissions reductions over the next two decades. Their anticipated pathway including nuclear deserves study, recognizing that for each nation there are specific factors that must influence their choices. The The Renewable Energy Review and supporting documents are important contributions.

I agree that "Of course it's not all sunshine and rainbows. Meeting the $5.1 trillion global renewable energy investment from 2011 to 2020 will require a five-fold increase from current investment levels. And of course there is the political challenge involved in implementing the necessary policies to allow this renewable energy investment increase to happen". Also support this report with a few hints.
What about natural disasters e.g.: volcanic emissions, the impact of the earthquake, wind, etc.. Of course scenario is attainable, but in the report is only mentioned mitigation and therefore I 'think' based on the examples that I mentioned about report are need 'small corrections and additions' to the report, and should turn attention mechanisms of the adaptation. Guided by the idea that we have to adapt to the nature and not vice versa. I apologize if someone understood this comment as a malicious. Thanks.

Lets not forget that even as late as 2009, global subsidies for the fossil fuel industry totaled just over US$300 billion per annum, whereas global subsidies for renewable energy is little more than US$20 billion-yet even with this massive discrepancy, renewable energy has made massive inroads in their production costs. Imagine where they would be by comparison if they halved fossil fuel subsidies & transferred them to renewable energy instead?

I've also noticed something quite disturbing....though maybe I shouldn't be surprised. Countries like Australia & the US generate a *lot* of surplus energy which isn't getting used. Australia generates around 30TWh of electricity per year more than what it uses (& given how inefficiently we currently use electricity, that's *REALLY* saying something), & the US generates around 250TWh of surplus electricity (minus exports). I wonder if this is a legacy of large, centralized generation facilities that are incapable of properly matching supply to demand and/or which are losing energy during transmission & distribution. Renewable Energy systems tend to be better in this regard because they can be built closer to the site of demand, & tailored better to energy demand at different times of the day & night!

Marcus @46, when I worked at a power station in Mt Isa, they had four boilers. Two were needed to supply the town and mines. One was always down for routine maintenance, and one was kept operating on standby in case of failure by either of the two operational boilers. That way, in the event of failure, they could have a new boiler up to full power in 15 minutes rather than the several hours it would take for a cold start. That practise may well be fairly general, and may account for a significant fraction of the unused power.

Well its actually really hard to tell from those graphs, Quokka, but I know that Australia's Fossil Fuel industry receives about $9.2 billion in Government Subsidies, & the US industry receives at *least* $40 billion in Federal Subsidies *alone* (don't know what it equates. If this is anything to go by, I'd guess its fair to say that close to half of the $560 billion in fossil fuel industry subsidies is being spent in OECD countries-like Germany, Australia, Japan, the UK & Canada.
Even so, the fact that its the Developing Nations which are spending so much money subsidizing Fossil Fuels-rather than renewable energy-does not negate my argument that the only reason fossil fuels are so cheap is because of decades of tax-payer funded support. After all, if the industry is so mature, then they should be able to provide cheap energy in developing nations *without* the need for massive subsidies! My main point is that the whole "cheap" fossil fuels thing seems to be a major case of False Economy-especially when you consider that most renewable energy technologies have gotten within spitting distance of fossil fuels *without* the need for such costly subsidies!

Let's get one thing straight - I am not arguing that subsidies are a good thing or for that matter that in all cases they are necessarily a bad thing. These are complex issues and require careful analysis.

But to argue that cost differentials in energy technologies is principally due to subsidies is extremely dubious. Furthermore, to come to any specific conclusion on decarbonization effects based on past expenditure on subsidies is folly. That is sunk cost, what matters today and in the coming decades is current and future costs.

There are many reasons for cost differentials and some of them are based in physical reality. One physical reality is energy density. This is one reason I believe that some renewables can never be as cheap as chips. Wind and CSP need lots of materials - steel concrete etc - and a lot of land. A lot more than for example does nuclear - by an order of magnitude or more. This is no going to change.

Trivializing energy analysis with a blind belief that infinite subsidies can, as if by magic, and by a wave of the hand dismiss physical and engineering realities is not going to get us a long way. It is much more complex than that.